[Porosity of hard dental tissues]

The examination of the porosity of hard dental tissues and the Zn-phosphate cement was carried out with the mercury-porosimeter (Carlo Erba, Italy mod. 2000) under the atmospheric pressure of 200 MPA. The accuracy of this method does not permit measurements of the porosity of enamel, more precisely the enamel surface cannot be permeated by mercury. The total volume of opened pores of the examined dentin was considerably high (28 cm3/gr); the main characteristics of dentin porosity are: the prevalence of macropores (2R 200 nm) of which 40% with the diameter between 400 and 2000 nm and 40% with the diameter between 6000 and 150,000 nm the presence of pores with diameter between 50 and 400 nm, and over 100,000 nm was minimal. The specific porosity of dentin was found to be 60% greater in relation to the porosity of cement. In the cement the diameter between 4000 and 30,000 nm was found in the majority of pores (about 52%) and the remaining 48% belonged to the macropore groups. The specific porosity of Zn-phosphate cement was found to be five times greater in relation to the specific porosity of dental cement (0.082 to 0.016 cm3/gr). However, the prevalence of these specimens was that of mezo pores.